Keywords: dark, chocolate (PubMed Search)
Dark chocolate is being touted more and more as being beneficial to vascular health. It contains polyphenols which has been found to exert anti-oxidant effects and improve endothelial and platelet function. The benefit appears to occur anywhere from 2-8 hours after ingestion of dark chocolate. Unfortunately, the same has not been found true for white chocolate or milk chocolate.
The only caveat is that most of the studies seem to originate in Switzerland and are funded by the Mars Company and Nestle...but who care?? Go ahead and have some dark chocolate every day!
[Dark Chocolate Improves Endothelial and Platelet Function (Hermann F, Heart 2006); Cocoa and Cardiovascular Health (Corti R, Circulation 2009)]